<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>setAttribute</title>
        <style>
            .democlass{
                color:red;
            }
        </style>
    </head>
    <body>
        <h1>Hello World</h1>
        <p id="demo">点击按钮来删除标题中的 style 属性节点。</p>

        <button onclick="myFunction()">试一下</button>
        <script src="setAttributeNode.js"></script>
    </body>
</html>